Senior Product Engineer
Posted Aug 25, 2026 · We last checked this listing on Oct 6, 2026
Likely interview questions for this role
Written from this job description, not a generic list. Each one notes what the interviewer is really checking.
About your past
Tell me about a design-for-manufacturability issue you found and how you got the customer to change their design.
What they are checking: Whether they can influence a customer's engineers with evidence, since the customer owns the design.
Describe how you've supported a new product introduction from prototype to volume production.
What they are checking: Whether they've seen the full ramp and know what usually goes wrong between first builds and steady production.
Tell me about a time you mentored a junior engineer or technician on troubleshooting.
What they are checking: Whether a senior engineer builds others' skills, which helps the whole site keep up with customer demands.
What would you do
Yield on a printed circuit board assembly drops from 98 percent to 90 percent over two weeks. How do you investigate?
What they are checking: Whether they work methodically through data, process, materials and changes instead of jumping to one favorite cause.
A customer is upset about a field failure and wants answers today. You don't have them yet. What do you say?
What they are checking: Whether they stay honest about what is known while giving the customer a clear plan and timeline.
About the work
At a contract manufacturer like Plexus, what does a product engineer own between the customer's design and the build on the floor?
What they are checking: Whether they understand the bridge role of turning a customer's design into something the factory can build reliably.
Walk me through how you'd handle an engineering change order from a customer that affects parts already in inventory and work in process.
What they are checking: Whether they think through cutover, inventory, costs and documentation, where sloppy ECO handling causes mixed builds.
How do you decide whether a recurring defect is a design problem for the customer or a process problem for the factory?
What they are checking: Whether they can separate root causes fairly, which matters when the answer decides who pays to fix it.
How do you use test data, such as in-circuit or functional test results, to drive improvements?
What they are checking: Whether they treat test data as a source of insight, not just a pass or fail gate.
In medical or aerospace programs, what changes about how you make process or design changes?
What they are checking: Whether they respect validation, documentation and customer approval in regulated builds, where unapproved changes are serious.
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Practice this out loudThe full job description
As published by Plexus.